Muffler having outer shell deformed to define chambers around center tube



July 27, 1965 w. H. POWERS ETAL` 3,196,976

MUFFLER HAVING OUTER SHELL DEFORMED T0 DEFINE CHAMBERS AROUND CENTER TUBE Filed June 27, 1965 f MHP a, m H. 1&4/ Mr q l lll-Ill United States Patent O Signy/'6 MUFFLER HAVEN@ @UTER SHELL DEFURMED Tt) EFENE CHAMBERS AR'LUND CENTER TUBE Walter l. Powers, Racine, Wis., and Robert A. Heath, Jackson, Mich., assignors to Wailrer Manufacturing Company, Racine, Wis., a corporation of Delaware Filed lune 2.7, 1963, Ser. No. 291,1172 i@ Claims. (l. tgl- 43) Our invention relates to the silencing of gases and in particular is concerned with a silencing device that is well adapted for use in the exhaust systems of automobiles.

lt is an object of the invention to provide a silencing structure which may be inexpensively manufactured and which may, if desired, be used as a component in a small diameter, extended length, exhaust gas silencing system.

Another object of the invention is to provide a silencing System in which a simple manufacturing technique may `be used to connect an outer shell to an inner tube and the means of connection may be arranged to also provide a silencing component or a drainage element.

The invention, in its presently preferred form, cornprises an inner gas conduit which is perforated or louvered along its length and which is surrounded by a larger diameter shell so that there is a chamber formed between the outer shell and the inner conduit. The outer shell is pinched down at different radial points along its length so that the pinched portions engage the inner conduit to attach and support the outer shell to the inner conduit. Additionally, the pinched-down portions divide the space between the outer shell and the inner conduit into a series of longitudinally separated silencing chambers. The pinched-down portions which are located on the bottom of the assembly when the assembly is in use are left open so that there is a continuous channel from one end of the shell to the other to permit the flow of liquid, such as condensate or materials used in internal coating process (such as a ceramic coating process) to flow freely from one end of the assembly to the other. Furthermore, one or more of the pinched-down sections may be of such width and such length as to form a structure having an acoustic effect, such as a tuning neck for a tuning chamber. The pinched-down portions are so located and preierably the diameter of the shell and pipe is such that the assembly may be bent to various angles so that it is adapted for use as a bendable tailpipe silencing and exhaust conduit system for modern automobiles.

The invention is illustrated in the accompanying drawings in which:

FIGURE l is a longitudinal cross section through an illustrative form of the invention;

FIG. 2 is a sectional along the line 2 2 of FGURE 1;

lil-LG. 3 is a sectional on the line 3-3 of FIGURE l; and

FG. 4 is a side elevation broken away showing the eX- ternal appearance of the assembly.

The silencing assembly ll comprises only two parts, an inner conduit 3 and an outer shell 5. it is contemplated that for most automotive usages the conduit 3 will be about 2 inches in diameter and the shell 5 about 3 inches in diameter.

In accordance with the invention, the shell Sis reduced in diameter at various longitudinal sections so that it is tightly attached to be conduit 3. The reduced down sections may, and preferably are, spotwelded to the conduit 3 so as to securely attach the two parts together. Thus the outer shell S is reduced in diameter at the inlet and outlet ends 7 and 9 respectively, and at intermediate longitudinal portions llt, i3, and l5. The reduced diameter sections 7 and 9 close off the ends of the shell 5 and reduced sections lll, lli, and l5 divide the interior space between the conduit 3 and the shell 5 reduced section lil to provide into four acoustic chambers i7, 19, 2l., and 23. That portion of the tube 3 which is inside of the chambers il?, 21, and 23 is louvered as indicated by the louver openings 25. However, the portion of the tube 3 which is in the chamber i7 and that portion which is coextensive with the reduced section 11, may be imperforate, as shown, so as to illustrate different eiects obtained with the invention. lt will be immediately recognized that the chambers 1&9, 2i, and 23 in combination with the louvers 25 will function as high frequency or spit chambers to silence high frequency noises and roughness in the exhaust gases passing through the conduit 3.

The reduced diameter sections 7, il, 13, 1S, and 9 are all formed in substantially the same mannar so that a description of one will disclose how the others can be manufactured. It may be noted, however, that the extreme radial ends of the sections 7 and 9 may be arc welded if desired, to provide a positive metal closure to prevent escape of gas from chambers 17 or 23. The location of such arc welds, if used, is indicated by the reference numerals 27.

The reduced section i3 is formed by pinching the shell 5 together at four equally spaced points 29, 31, 33 and 3S. When this is done the metal is reversely bent upon itself in double layer bites or V-shaped folds. In the case of the bites 29, 3l, and 33 the two layers are preferably in contact with each other. However, the bite 35 is formed so that the two layers are spaced from each other to form a channel 37, this being located on the bottom side of the assembly l when it is in use so that liquid will tend to accumulate in the channel 37. The sections of the joint i3 located between the various bites 29, 3l, 33 and 35 necked down and in circumferential contact with the outside of the tube 3, as seenat 39, 4l, 43, and 45. One or more of these sections may be spotwelded to the conduit 3 and the various bites 29, 3l, 33 may be spotwelded together if desired. The objective, of course, is Ito obtain suit-able tightness of the joint 13 to prevent longitudinal shifting of the shell 5 relative to the conduit 3 and to provide fluid tightness.

At the joint 7 all of the bites will be formed in a manner similar to bites 29, 3l and 33 so that the inlet end is not open to atmosphere. At the outlet end the bites may be formed in the same way as the inlet end or, alternatively, the bottom bite corresponding to bite 35, may be opened just a slight amount, less than the bite 35, so that any accumulated liquid or condensate can drain externally out of the shell 5 but without negative acoustic consequences. The joint 1S, of course, is formed in an identical manner to the joint 13.

The joint lll may be formed in a similar manner to the joint 13 but it is illustrated as being of substantially greater length. This is done so as to enable the channel 37a formed by the bite 35a at the bottom of the an acoustic effect.

it will be noted that the chamber ll'.l is connected to the gas flow only by means of the channel 37a since the pipe 3 is imperforate in that portion which is inside of the chamber 17. Thus, the channel 37a can serve as a tuning neck and the chamber 17 as a tuning chamber to silence desired frequency within the dimensional capabilities of the structure. It is clear that the dimensions of channel 37a can be altered as can the dimensions of chamber i7 to obtain the desired silencing eifect. Additionally, other of the bites at the reduced section 11 can be opened to provide plural or other tuning necks for chamber i7.

Since the channel 37a is open it bottom channels at reduced neck permit accumulated liquid to of the shell to the other. lated condensate to be will act with the open sections 13 and 1S to iiow freely from one end This will permit any accumupicked up by vaporzation into the and spit chambers as shown,

gas and carried out through the conduit 3 or if a `slight opening is provided at the outlet end 9 in the bottom bite, it may be able to drain as a liquid out of the end of the shell.

While the various bites have been shown as in longitudinal alignment, it is apparent that they could be rotated to different angular positions so as to facilitate bending of the assembly l.

For external drainage from the inside to the outside of shell 5, instead of the open bite at the end 9, a hole may actually be drilled in the shell if desired.

if the unit is to be ceramic coated by dipping in a series of preparatory and coating liquids, an opening may be formed at the inlet end 7 so as to provide openings at opposite ends of the chamber 17 to provide for adequate venting and drainage of the chamber. Such an opening would be closed by means of a plug or by means of metal deformation or ceramic buildup prior to usage of the unit 1.

'The structure described above is clearly susceptible of many modifications so as to adapt itself to the particular requirements of any given exhaust system application. Thus within the broad purview of the invention, it is not necessary that there be a combination of tuning chambers one or the other may be used exclusively. Gther types of silencing components can be utilized. The chambers, or one or more of them, may be packed with a suitable sound absorbing material such as steel wool or glass wool. 'The structure is especially well adapted for chamber pipe applications in which the shell 5 will actually be the outermost portion of the assembly. lf it is not ceramic coated it may be wrapped with an outer layer of metal or metal and asbestos, etc., in accordance with techniques already known in the automative silencing industry. if desired, however, the assembly 1l may be a part of a larger assembly, that is, it may be used inside of a typical exhaust muffler in which case the shell 5 would be enclosed by a larger and outer shell. ln such case it may be desirable to open up one or the other of the ends 7 and 9 and increase the length of the joint so as to provide a channel corresponding to 37a opening into the larger chamber that would be surrounding the assembly 1.

Modifications may be made without departing from the spirit and scope of the invention.V

We claim:

1. A small diameter bendable multi-chamber silencing device for automotive exhaust systems comprising a center tube and an outer shell around the center tube, said outer shell having radial sections reduced in diameter to contact and t around the center tube and form a plurality of longitudinally separated chambers around the center tube, each of said sections comprising a plurality of V-shaped folds and passage means in the shell provided by one of said folds and serving to intercommunicate at least an adiacent pair of said chambers.

2. 'The invention set forth in claim 1l wherein said passage means intercommunicates all of the chambers and provides for inter-chamber drainage.

E. The invention set forth in claim 2 wherein said passage means is located on the bottom of the shell when it is in use and provides inter-chamber condensate drainage among all the chambers.

4. T he invention set forth in claim 1l wherein said passage means is of substantial length and acts as an acoustic element.

5. The invention set forth in claim 4 wherein one of the chambers connected to the passage means is closed entirely except for said passage means and said passage means acts as a tuning tube for said chamber.

6. The invention set forth in claim 1l wherein said passage means is located on the bottom of the device in use and serves to provide drainage between the chambers and is an acoustic element.

7. A small diameter multi-chamber silencing device comprising a center tube and an outer shell around the center tube, said outer shell having radial sections comprising deformed portions and V-shaped fold portions, said deformed portions being in peripheral contact around the center tube to define a series of longitudinally separated chambers around the tube, said V-shaped fold portions providing passage rneans through said radial sections at the outer diameters thereof to intercommunicate all the chambers.

8. The invention set forth in claim 7 wherein at least one of said radial sections is of substantial length whereby the passage means therein, acts as a tuning tube for connection with a chamber tuned therewith.

9. A two-part silencing assembly comprising an inner conduit and an outer shell, said outer shell having a plurality of longitudinally spaced reduced diameter sections formed therein and defining a series of chambers between the inner conduit and said shell, at least one of said reduced diameter sections having V-shaped fold portions and portions tightly engaging the outer periphery of said inner conduit, one of said V-shaped fold portions being located on the bottom of the assembly and being open to provide a channel communicating the chambers on the opposite sides of said one reduced diameter section.

1 0. A two-part silencing assembly for use in automotive exhaust systems or the like, comprising a gas conduit and a shell positioned around said conduit and spaced from it, said shell having a plurality of reduced diameter sections formed therein and defining a series of longitudinally spaced chambers between said conduit and said shell, each of said reduced diameter sections having V-shaped fold portions and portions tightly engaging the outer periphery of the conduit, one of the fold portions of cach of said sections being open to provide a channel connecting the chambers on the opposite sides of each of the sections, said conduit being imperforate in one of the chambers, at least one of said sections being of a length and cross-sectional area to provide a tuning neck associated with said one chamber, said chamber and tuning neck being adapted to silence predetermined frequencies, said conduit being louvered in the chamber adjacent the inletV end of the tuning neck chamber.

References (Cited bythe Exaer UNlTED STATES PATENTS 1,603,910 10/26 Enger 181-72 X 2,018,084 10/35 Oldberg 181-53 2,047,443 7/ 36 Starkweather et al. 2,084,435 6/37 Deremer 181-72 X 2,088,296 7/37 Kingsley 181-48 2,099,858 11/37 MacKenzie et al 181-48 2,191,619 2/40 Muller 181-48 2,194,457 3/40 Cary 181-48 X 2,332,543 10/43 Wilson 181-48 2,367,753 1/ 45 Buck. 2,770,313 11/56 Johnson. 3,036,655 5/62 Powers 181-61 X 3,082,841 3/63 Powers 181-62 X 3,104,735 9/ 63 Ludlow et al. 181-48 3,118,517 1/64 Ludlow et al.

- FOREIGN PATENTS 892,780 3/ 62 Great Britain.

LEO SMlLOW, Primary Examiner, 

1. A SMALL DIAMETER BENDABLE MULTI-CHAMBER SILENCING DEVICE FOR AUTOMOTIVE EXHAUST SYSTEMS COMPRISING A CENTER TUBE AND AN OUTER SHELL AROUND THE CENTER TUBE, SAID OUTER SHELL HAVING RADIAL SECTIONS REDUCED IN DIAMETER TO CONTACT AND FIT AROUND THE CENTER TUBE AND FORM A PLURALITY OF LONGITUDINALLY SEPARATED CHAMBERS AROUND THE CENTER TUBE, EACH OF SAID SECTIONS COMPRISING A PLURALITY OF V-SHAPED FOLDS AND PASSAGE MEANS IN THE SHELL PROVIDED BY ONE OF SAID FOLDS AND SERVING TO INTERCOMMUNICATE AT LEAST AN ADJACENT PAIR OF SAID CHAMBERS. 